J Clin Periodontol 2014; 41 (Suppl. 15): S77–S91 doi: 10.1111/jcpe.12220
Efficacy of soft tissue augmentation around dental implants and in partially edentulous areas: a systematic review
Daniel S. Thoma1, Borvornwut Buranawat1, Christoph H.F. €mmerle1, Ulrike Held2 and Ha Ronald E. Jung1 1
Clinic of Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich, Zurich, Switzerland; 2 Horten Centre for Patient Oriented Research and Knowledge Transfer, University Hospital Zurich, Zurich, Switzerland
Thoma DS, Buranawat B, H€ ammerle CHF, Held U, Jung RE. Efficacy of soft tissue augmentation around dental implants and in partially edentulous areas: A systematic review. J Clin Periodontol 2014; 41 (Suppl. 15): S77–S91. doi: 10.1111/jcpe.12220.
Abstract Aim: To review the dental literature in terms of efficacy of soft tissue augmentation procedures around dental implants and in partially edentulous sites. Methods: A Medline search was performed for human studies augmenting keratinized mucosa (KM) and soft tissue volume around implants and in partially edentulous areas. Due to heterogeneity in between the studies, no meta-analyses could be performed. Results: Nine (KM) and eleven (volume) studies met the inclusion criteria. An apically positioned flap/vestibuloplasty (APF/V) plus a graft material [free gingival graft (FGG)/subepithelial connective tissue graft (SCTG)/collagen matrix (CM)] resulted in an increase of keratinized tissue (1.4–3.3 mm). Statistically significantly better outcomes were obtained for APF/V plus FGG/SCTG compared with controls (APF/V alone; no treatment) (p < 0.05). For surgery time and patient morbidity, statistically significantly more favourable outcomes were reported for CM compared to SCTGs (p < 0.05) in two randomized controlled clinical trials (RCTs), even though rendering less keratinized tissue. SCTGs were the best-documented method for gain of soft tissue volume at implant sites and partially edentulous sites. Aesthetically at immediate implant sites, better papilla fill and higher marginal mucosal levels were obtained using SCTGs compared to non-grafted sites. Conclusions: An APF/V plus FGG/SCTG was the best-documented and most successful method to increase the width of KM. APF/V plus CM demonstrated less gain in KM, but also less patient morbidity and surgery time compared to APF/V plus SCTG based on two RCTs. Autogenous grafts (SCTG) rendered an increase in soft tissue thickness and better aesthetics compared to non-grafted sites.
Key words: allogenic dermal matrix graft; collagen matrix; dental implant; free gingival graft; keratinized tissue; soft tissue augmentation; soft tissue volume; subepithelial connective tissue graft; vestibuloplasty Accepted for publication 24 November 2013
Conflict of interest and source of funding statement This review was funded by the Clinic of Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich. Dres. H€ammerle, Jung and Thoma have received lecture fees from Geistlich Pharma AG, Wolhusen, Switzerland and are member (Jung, Thoma) of the Osteology Foundation Expert Council or president (H€ ammerle) of the Osteology Foundation. Other than mentioned, the authors do not report any conflict of interest for this study. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
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Plastic periodontal procedures to augment keratinized tissue and to increase soft tissue volume are well described (Cairo et al. 2008, Thoma et al. 2009). These procedures are indicated to establish functional and biological stability around teeth and implants, mainly in conjunction with reconstructive therapy. The question whether there is a need for keratinized tissue to maintain periodontal health around teeth and peri-implant health around dental implants has been controversially discussed in the literature citing a number of parameters to be considered: (i) establishment and maintenance of biological health; (ii) prevention of recession; (iii) aesthetics; and (iv) cleansibility of the reconstruction (Hoelscher & Simons 1994, Marquez 2004, Mehta & Lim 2010, Wennstrom & Derks 2012). For dental implants, clinical evidence suggests that a lack of keratinized mucosa (KM) may not be crucial in maintaining the health of peri-implant soft tissues (Wennstrom et al. 1994), may not be associated with more bone loss (Chung et al. 2006) or that despite the presence of KM, peri-implantitis may occur (Roos-Jansaker et al. 2006). In contrast, more recent clinical studies concluded that a wider zone of KM may better preserve soft and hard tissue stability (Bouri et al. 2008), may be more favourable for the long-term maintenance of dental implants (Kim et al. 2009) and that a lack of KM may result in poorer oral hygiene and greater soft tissue recession (Schrott et al. 2009). This resulted in a clinical recommendation of 2 mm for the width of KM (Bengazi et al. 1996, Adibrad et al. 2009), a dimension similar to the zone of keratinized gingiva recommended to be adequate around teeth (Lang & Loe 1972). Treatment-wise, plastic procedures to augment keratinized tissue include an apically positioned flap or a vestibuloplasty procedure (Palacci & Nowzari 2008, Thoma et al. 2009). This can be performed prior to implant placement, simultaneously with second stage surgery or post insertion of the final reconstruction. Moreover, to compensate for hard and soft tissue deficits in localized defects, soft tissue volume augmentation is mainly indicated for aesthetic reasons and to facilitate oral hygiene in pontic areas
(Seibert 1983a, Pini-Prato et al. 2004). In these sites, the classic procedures include the use of free gingival grafts (FGG), subepithelial connective grafts (SCTG) and various types of roll and pedicle flaps (Seibert 1983b, Cho 1998, Studer et al. 2000, Batista et al. 2001, Breault et al. 2004). In conjunction with dental implants, plastic augmentative procedures were recommended to enhance the thickness of the soft tissues simultaneously with implant placement or during the healing phase of the implants (Grunder 2000, Speroni et al. 2010, Schneider et al. 2011). Clinical studies demonstrated various techniques to be successful, resulting in greater flexibility for the choice of the reconstruction material, better aesthetic outcomes with respect to the colour of the peri-implant tissues, maintenance or even improvement of the marginal mucosal height and higher papillae scores (Cornelini et al. 2008, Jung et al. 2008, Kan et al. 2009, Speroni et al. 2010). From a functional point of view, however, there is still a lack of scientific evidence whether thicker peri-implant soft tissues result in better long-term success and survival rates of dental implants. Since controversy still exists with respect to the efficacy of soft tissue augmentation and new materials were evaluated more recently, there is a strong need to critically assess the dental literature for optimized procedures and graft materials in terms of soft tissue augmentation. Therefore, the aim of the present systematic review was to assess dental literature focusing on the efficacy of soft tissue augmentation procedures to increase the width of the KM around dental implants and to increase the soft tissue volume around implants and in partially edentulous areas. Materials and Methods Protocol development and eligibility criteria
A detailed protocol was developed and followed according to the PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analyses) statement (Liberati et al. 2009, Moher et al. 2009).
Focused question
What is the efficacy of different soft tissue augmentation methods in terms of (i) increasing the width of KM and (ii) gain in soft tissue volume around implants and in partially edentulous areas? Search strategy
A Medline (PubMed) search was performed for human studies, including articles published from 1 January 1966 up to 15 May 2013 in the dental literature. The search was limited to the English and German language. The search was complemented by manual searches of the reference list of all selected full-text articles. In addition, full text articles of reviews published in the same time period were obtained. An additional hand search was performed searching for relevant studies by screening these reviews. Search terms
The following search terms were selected: “acellular dermal matrix” OR “dermal matrix allograft” OR “alloderm” OR “keratinized gingiva” OR “keratinized tissue” OR “soft tissue graft” OR “subepithelial connective tissue graft” OR “connective tissue” OR “FGG” OR “human fibroblast-derived dermal substitute” OR “dermagraft” OR “apligraf” OR “collagen matrix” OR “extracellular membrane” OR “gingival autograft” OR “attached gingiva” OR “attached mucosa” OR “KM” OR “soft tissue augmentation” OR “soft tissue transplantation” OR “vestibuloplasty” OR “ridge augmentation” OR “soft tissue correction” OR “apically positioned flap” AND “dental implants” OR “Jaw, Edentulous, Partially” OR “pontic” (all MeSH terms). The search was limited to language (English, German), “human trial” (MeSH term, clinical studies), and “Dental Journals”. In addition, the MeSH terms: “case reports”, “clinical trial”, “comparative study”, “controlled clinical trial (CCT)”, “randomized controlled clinical trial (RCT)”, “meta-analysis”, “review” and “systematic reviews” were used. Inclusion criteria
The applied inclusion criteria for studies dealing with gain of KM or
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Soft tissue grafting: a systematic review gain of soft tissue volume were as follows: Increase in width of keratinized mucosa
Any case series, cohort study, CCT and RCT with at least five patients was included. A follow-up period of at least 3 months was required for the primary outcome “gain in KM”. The reported treatment outcomes had to include either clinical and/or histological measures of the width of KM. The primary outcome of the studies had to be localized gain in width of KM. Augmentation of soft tissue volume around dental implant and in partially edentulous areas
For studies focusing on soft tissue volume gain, any prospective case series, cohort study, CCT and RCT with at least five patients was included. The minimal follow-up time was 3 months for the primary outcome “gain in soft tissue volume”. The reported treatment outcomes had to include either clinical and/or histological measures of the soft tissue volume. The minimal follow-up time (3 months) for the primary outcome variables chosen in this systematic review is based on a lack of a scientific data with long-term results and in line with a previously published systematic review (Thoma et al. 2009). Exclusion criteria
Studies not meeting all inclusion criteria were excluded from the review. Publications dealing with the following topics were also excluded: in vitro studies, pre-clinical (animal) studies, studies dealing with the treatment of recession defects, studies augmenting keratinized tissue around teeth only, studies augmenting soft tissue in fully edentulous patients, studies where the effect of soft tissue augmentation surgery could not be extracted from the data (e.g. combination of guided bone regeneration and soft tissue augmentation). Selection of studies
Titles derived from this broad search were independently screened by two authors (DT, BB) based on the inclu-
sion criteria. Disagreements were resolved by discussion. Cohen’s Kappacoefficient was used as a measure of agreement between the two readers. Following this, abstracts of all titles agreed on by both authors were obtained, and screened for meeting the inclusion criteria. If no abstract was available in the database, the abstract of the printed article was used. The selected articles were then obtained in full text. If title and abstract did not provide sufficient information regarding the inclusion criteria, the full report was obtained as well. Again, disagreements were resolved by discussion. Finally, the selection based on inclusion/exclusion criteria was made for the full text articles. For this purpose, Material and Methods and Results of these studies were screened. This step was again carried out independently by two readers. Disagreements were resolved by discussion. Data extraction
Two reviewers independently extracted the data using data extraction tables. Any disagreements were resolved by discussion aiming for consensus. Quality assessment
A quality assessment of the included RCTs and controlled clinical studies was performed independently by two reviewers (BB, DTH) according to the Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 (updated March 2011) (Higgins & Green 2011). Three main quality criteria were assessed: allocation concealment, blinding treatment outcomes to outcome examiners and completeness of follow-up. The studies were then rated to have a low risk of bias (all three criteria met) or a high risk of bias (one or more criteria not met). Statistical analysis
Means and standard deviations were calculated for a number of outcome parameters. No meta-analyses could be performed due to heterogeneity in between the studies (different indications, study designs, control groups, observation periods).
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
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Results Study characteristics
The electronic search identified a total of 2396 titles (for details, refer to Fig. 1). From assessing the titles, 2283 were excluded (inter-reader agreement k = 0.98 0.48). The resulting number of abstracts obtained was 113, of which 83 were excluded (inter-reader agreement k = 0.98 0.25). Thirty full-text articles were obtained, seven articles were further excluded after reading the full text. Finally, including studies found through hand searching, nine studies of keratinized tissue and 11 studies of soft tissue volume articles met the inclusion criteria. Exclusion of studies
The reasons for excluding studies (7) after full text was obtained were no reported or insufficient clinical details (n = 3), an insufficient number of patients (n = 1), only hard tissue augmentation (n = 2) and soft tissue augmentation in combination with implant placement and guided bone regeneration (n = 1). Details are provided in Table 1. Included studies
The 20 studies that met the inclusion criteria are presented in Tables 2–5. Tables 2 and 4 represent data for “gain of keratinized tissue” (nine studies) and Tables 3 and 5 refer to clinical studies regarding “soft tissue volume” (11 studies). Increase in width of keratinized mucosa
Patient-based treatment outcomes for the width of keratinized tissue retrieved from nine studies are presented in Tables 2 and 4. Three studies were designed as RCT, two as CCT and the rest of four studies were case series reports. 283 patients and 375 sites were treated for gain of keratinized tissue around the implants. The methods and techniques used for gain of keratinized tissue included no treatment, vestibuloplasty, apically positioned flap/vestibuloplasty (APF/ V) in combination with autogenous tissues FGG, SCTG and APF/V in combination with allogenic grafts (ADMG) or collagen matrices (CM). The mean follow-up period was
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Thoma et al. Basegmez et al. 2012, Lorenzo et al. 2012).
First electronic search: 2396 titles
Treatment outcomes Inter-reader agreement k = 0.98 ± 0.48
Independently selected by 2 reviewers and agreed by both: 113 titles abstracts obtained
Inter-reader agreement k = 0.98 ± 0.25
Independently selected by 2 reviewers and agreed by both: 30 abstracts full text obtained
Excluded: 7
Keratinized tissue: 3
Review: 11
Soft tissue volume: 9
Further handsearching 6 articles on keratinized tissue (references of full text articles)
Further handsearching 2 articles on soft tissue volume (references of full text articles)
Final number of studies included keratinized tissue: 9
Final number of studies included soft tissue volume: 11
Further handsearching 2 articles (references of full text articles)
Final number of reviews included for hand search: 13
Fig. 1. Search strategy.
Table 1. Excluded studies with reason for exclusion Author Alpert (1994) Becker (2001) Bidra & Rungruanganunt (2011) Collins & Nunn (1994) Fagan et al. (2008) Kwakman et al. (1998) Liu & Weisgold (2002)
16.2 months (6–48). The main reason for treating the patients encompassed a lack of or an inadequate with of attached gingival/keratinized tissue. In summary, three studies were eligible for comparison using meta-analyses. The hypothesis of the heterogeneity test could not be rejected (p = 0.43);
Reason for exclusion Only descriptive, no data Hard tissue only Two cases only Hard tissue augmentation only No data, immediate implant placement and soft tissue augmentation at the same time No detailed information about procedures No data, only classifications
therefore, a fixed effects model was chosen. Quality assessment The quality assessment of the included studies revealed a high risk of bias for all included studies except for the three RCTs (Sanz et al. 2009,
Width of keratinized tissue. A total of seven studies (three RCTs, two CCTs, two case series) reported on the width of augmented keratinized tissue. The increase in keratinized tissue ranged between 1.4 and 3.3 mm depending on the technique used. Four studies investigated the efficacy of collagen matrices (Mucograftâ, Geistlich, Wolhusen, Switzerland and Collatapeâ, Zimmer Dental, Carlsbad, CA, USA) (gain between 1.8 and 2.3 mm) or an acellular dermal matrix graft (SureDermTM, Hans Biomed Corp, Seoul, Korea) (gain of 1.4 mm) compared to autogenous grafts (FGG, SCTG) for augmenting the band of keratinized tissue. In two RCTs, the application of a CM (gain of 1.8– 2.3 mm) demonstrated a gain of keratinized tissue as effective and predictable as the gold standard, an autogenous SCTG (gain of 2.3 mm; Sanz et al. 2009, Lorenzo et al. 2012). One study evaluated the changes in width of keratinized tissue following APF/V, APF/V plus CM and APF/V plus FGG. After 3– 4 weeks, the FGG cases showed a greater increase in keratinized tissue (2.5 mm), while the APF/V plus CM (1.8 mm) demonstrated a more physiological and a more favourable morphology than the APF/V only cases (1.6 mm) (Lee et al. 2010). In addition, one study reported on the effects of different time-points for performing FGGs (Stimmelmayr et al. 2011). In this study, no statistical significance (p = 0.562) was found in width of keratinized tissue between FGGs performed at the time of implant placement or at the time of uncovering the implants (Stimmelmayr et al. 2011). The mean gain of keratinized tissue for APF/V plus FGG ranged between 2.2 and 3.3 mm. Percent shrinkage or contraction of keratinized tissue. Two RCTs (Sanz et al. 2009, Basegmez et al. 2012) and one case series (Park 2006) reported post-operative shrinkage or contraction of augmented tissue. All studies found shrinkage of the augmented grafts (SCTG, CM, ADMG, FGG). Only one study reported on
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
NA APF/V in combination with implant placement
NA APF/V plus FGG
2011
2012
2012
Stimmelmayr et al. (2011)
Basegmez et al. (2012)
Bruschi et al. (2012)
Case series
Inadequate width of attached mucosa 3 mm; APF/V2-3 mm; APF/V plus CMminimal; APF/V plus FGG Inadequate width of keratinized mucosa ≤1 mm Inadequate width of keratinized tissue (≤ 3.5 mm) Case series
1991 ten Bruggenkate et al. (1991)
Case series
Inadequate width of keratinized mucosa ≤2 mm on both sides of the implant Inadequate width of attached gingiva Case series
NA APF/V plus CTG APF/V plus CM (Mucograft)
6 APF/V plus FGG APF/V APF/V plus CM (Collatape)
6 APF/V plus SCTG APF/V plus CM (Mucograft)
NA
NA NA
6
NA No treatment
APF/V in combination with implant placement APF/V plus ADMG
18
NA NA APF/V plus FGG
6–32
Control 2 treatment Indication for treatment Study design Year of publication Author
Table 2. Included studies: augmentation of keratinized mucosa
Test treatment
Control 1 treatment
Follow-up period (months)
Soft tissue grafting: a systematic review
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% mean graft contraction, revealing more favourable results for the autogenous control group (SCTG; 59.7%) compared to a CM group (67.2%) at 30 days (Sanz et al. 2009). Width of attached mucosa. One RCT study (Basegmez et al. 2012) reported on the efficacy of two techniques (APF/V + FGG or APF/V alone) for increasing the amount of keratinized tissue around the implants. Sixtyfour patients with 64 implants with a minimal keratinized tissue (
Efficacy of soft tissue augmentation around dental implants and in partially edentulous areas: a systematic review
Daniel S. Thoma1, Borvornwut Buranawat1, Christoph H.F. €mmerle1, Ulrike Held2 and Ha Ronald E. Jung1 1
Clinic of Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich, Zurich, Switzerland; 2 Horten Centre for Patient Oriented Research and Knowledge Transfer, University Hospital Zurich, Zurich, Switzerland
Thoma DS, Buranawat B, H€ ammerle CHF, Held U, Jung RE. Efficacy of soft tissue augmentation around dental implants and in partially edentulous areas: A systematic review. J Clin Periodontol 2014; 41 (Suppl. 15): S77–S91. doi: 10.1111/jcpe.12220.
Abstract Aim: To review the dental literature in terms of efficacy of soft tissue augmentation procedures around dental implants and in partially edentulous sites. Methods: A Medline search was performed for human studies augmenting keratinized mucosa (KM) and soft tissue volume around implants and in partially edentulous areas. Due to heterogeneity in between the studies, no meta-analyses could be performed. Results: Nine (KM) and eleven (volume) studies met the inclusion criteria. An apically positioned flap/vestibuloplasty (APF/V) plus a graft material [free gingival graft (FGG)/subepithelial connective tissue graft (SCTG)/collagen matrix (CM)] resulted in an increase of keratinized tissue (1.4–3.3 mm). Statistically significantly better outcomes were obtained for APF/V plus FGG/SCTG compared with controls (APF/V alone; no treatment) (p < 0.05). For surgery time and patient morbidity, statistically significantly more favourable outcomes were reported for CM compared to SCTGs (p < 0.05) in two randomized controlled clinical trials (RCTs), even though rendering less keratinized tissue. SCTGs were the best-documented method for gain of soft tissue volume at implant sites and partially edentulous sites. Aesthetically at immediate implant sites, better papilla fill and higher marginal mucosal levels were obtained using SCTGs compared to non-grafted sites. Conclusions: An APF/V plus FGG/SCTG was the best-documented and most successful method to increase the width of KM. APF/V plus CM demonstrated less gain in KM, but also less patient morbidity and surgery time compared to APF/V plus SCTG based on two RCTs. Autogenous grafts (SCTG) rendered an increase in soft tissue thickness and better aesthetics compared to non-grafted sites.
Key words: allogenic dermal matrix graft; collagen matrix; dental implant; free gingival graft; keratinized tissue; soft tissue augmentation; soft tissue volume; subepithelial connective tissue graft; vestibuloplasty Accepted for publication 24 November 2013
Conflict of interest and source of funding statement This review was funded by the Clinic of Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich. Dres. H€ammerle, Jung and Thoma have received lecture fees from Geistlich Pharma AG, Wolhusen, Switzerland and are member (Jung, Thoma) of the Osteology Foundation Expert Council or president (H€ ammerle) of the Osteology Foundation. Other than mentioned, the authors do not report any conflict of interest for this study. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
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Thoma et al.
Plastic periodontal procedures to augment keratinized tissue and to increase soft tissue volume are well described (Cairo et al. 2008, Thoma et al. 2009). These procedures are indicated to establish functional and biological stability around teeth and implants, mainly in conjunction with reconstructive therapy. The question whether there is a need for keratinized tissue to maintain periodontal health around teeth and peri-implant health around dental implants has been controversially discussed in the literature citing a number of parameters to be considered: (i) establishment and maintenance of biological health; (ii) prevention of recession; (iii) aesthetics; and (iv) cleansibility of the reconstruction (Hoelscher & Simons 1994, Marquez 2004, Mehta & Lim 2010, Wennstrom & Derks 2012). For dental implants, clinical evidence suggests that a lack of keratinized mucosa (KM) may not be crucial in maintaining the health of peri-implant soft tissues (Wennstrom et al. 1994), may not be associated with more bone loss (Chung et al. 2006) or that despite the presence of KM, peri-implantitis may occur (Roos-Jansaker et al. 2006). In contrast, more recent clinical studies concluded that a wider zone of KM may better preserve soft and hard tissue stability (Bouri et al. 2008), may be more favourable for the long-term maintenance of dental implants (Kim et al. 2009) and that a lack of KM may result in poorer oral hygiene and greater soft tissue recession (Schrott et al. 2009). This resulted in a clinical recommendation of 2 mm for the width of KM (Bengazi et al. 1996, Adibrad et al. 2009), a dimension similar to the zone of keratinized gingiva recommended to be adequate around teeth (Lang & Loe 1972). Treatment-wise, plastic procedures to augment keratinized tissue include an apically positioned flap or a vestibuloplasty procedure (Palacci & Nowzari 2008, Thoma et al. 2009). This can be performed prior to implant placement, simultaneously with second stage surgery or post insertion of the final reconstruction. Moreover, to compensate for hard and soft tissue deficits in localized defects, soft tissue volume augmentation is mainly indicated for aesthetic reasons and to facilitate oral hygiene in pontic areas
(Seibert 1983a, Pini-Prato et al. 2004). In these sites, the classic procedures include the use of free gingival grafts (FGG), subepithelial connective grafts (SCTG) and various types of roll and pedicle flaps (Seibert 1983b, Cho 1998, Studer et al. 2000, Batista et al. 2001, Breault et al. 2004). In conjunction with dental implants, plastic augmentative procedures were recommended to enhance the thickness of the soft tissues simultaneously with implant placement or during the healing phase of the implants (Grunder 2000, Speroni et al. 2010, Schneider et al. 2011). Clinical studies demonstrated various techniques to be successful, resulting in greater flexibility for the choice of the reconstruction material, better aesthetic outcomes with respect to the colour of the peri-implant tissues, maintenance or even improvement of the marginal mucosal height and higher papillae scores (Cornelini et al. 2008, Jung et al. 2008, Kan et al. 2009, Speroni et al. 2010). From a functional point of view, however, there is still a lack of scientific evidence whether thicker peri-implant soft tissues result in better long-term success and survival rates of dental implants. Since controversy still exists with respect to the efficacy of soft tissue augmentation and new materials were evaluated more recently, there is a strong need to critically assess the dental literature for optimized procedures and graft materials in terms of soft tissue augmentation. Therefore, the aim of the present systematic review was to assess dental literature focusing on the efficacy of soft tissue augmentation procedures to increase the width of the KM around dental implants and to increase the soft tissue volume around implants and in partially edentulous areas. Materials and Methods Protocol development and eligibility criteria
A detailed protocol was developed and followed according to the PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analyses) statement (Liberati et al. 2009, Moher et al. 2009).
Focused question
What is the efficacy of different soft tissue augmentation methods in terms of (i) increasing the width of KM and (ii) gain in soft tissue volume around implants and in partially edentulous areas? Search strategy
A Medline (PubMed) search was performed for human studies, including articles published from 1 January 1966 up to 15 May 2013 in the dental literature. The search was limited to the English and German language. The search was complemented by manual searches of the reference list of all selected full-text articles. In addition, full text articles of reviews published in the same time period were obtained. An additional hand search was performed searching for relevant studies by screening these reviews. Search terms
The following search terms were selected: “acellular dermal matrix” OR “dermal matrix allograft” OR “alloderm” OR “keratinized gingiva” OR “keratinized tissue” OR “soft tissue graft” OR “subepithelial connective tissue graft” OR “connective tissue” OR “FGG” OR “human fibroblast-derived dermal substitute” OR “dermagraft” OR “apligraf” OR “collagen matrix” OR “extracellular membrane” OR “gingival autograft” OR “attached gingiva” OR “attached mucosa” OR “KM” OR “soft tissue augmentation” OR “soft tissue transplantation” OR “vestibuloplasty” OR “ridge augmentation” OR “soft tissue correction” OR “apically positioned flap” AND “dental implants” OR “Jaw, Edentulous, Partially” OR “pontic” (all MeSH terms). The search was limited to language (English, German), “human trial” (MeSH term, clinical studies), and “Dental Journals”. In addition, the MeSH terms: “case reports”, “clinical trial”, “comparative study”, “controlled clinical trial (CCT)”, “randomized controlled clinical trial (RCT)”, “meta-analysis”, “review” and “systematic reviews” were used. Inclusion criteria
The applied inclusion criteria for studies dealing with gain of KM or
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Soft tissue grafting: a systematic review gain of soft tissue volume were as follows: Increase in width of keratinized mucosa
Any case series, cohort study, CCT and RCT with at least five patients was included. A follow-up period of at least 3 months was required for the primary outcome “gain in KM”. The reported treatment outcomes had to include either clinical and/or histological measures of the width of KM. The primary outcome of the studies had to be localized gain in width of KM. Augmentation of soft tissue volume around dental implant and in partially edentulous areas
For studies focusing on soft tissue volume gain, any prospective case series, cohort study, CCT and RCT with at least five patients was included. The minimal follow-up time was 3 months for the primary outcome “gain in soft tissue volume”. The reported treatment outcomes had to include either clinical and/or histological measures of the soft tissue volume. The minimal follow-up time (3 months) for the primary outcome variables chosen in this systematic review is based on a lack of a scientific data with long-term results and in line with a previously published systematic review (Thoma et al. 2009). Exclusion criteria
Studies not meeting all inclusion criteria were excluded from the review. Publications dealing with the following topics were also excluded: in vitro studies, pre-clinical (animal) studies, studies dealing with the treatment of recession defects, studies augmenting keratinized tissue around teeth only, studies augmenting soft tissue in fully edentulous patients, studies where the effect of soft tissue augmentation surgery could not be extracted from the data (e.g. combination of guided bone regeneration and soft tissue augmentation). Selection of studies
Titles derived from this broad search were independently screened by two authors (DT, BB) based on the inclu-
sion criteria. Disagreements were resolved by discussion. Cohen’s Kappacoefficient was used as a measure of agreement between the two readers. Following this, abstracts of all titles agreed on by both authors were obtained, and screened for meeting the inclusion criteria. If no abstract was available in the database, the abstract of the printed article was used. The selected articles were then obtained in full text. If title and abstract did not provide sufficient information regarding the inclusion criteria, the full report was obtained as well. Again, disagreements were resolved by discussion. Finally, the selection based on inclusion/exclusion criteria was made for the full text articles. For this purpose, Material and Methods and Results of these studies were screened. This step was again carried out independently by two readers. Disagreements were resolved by discussion. Data extraction
Two reviewers independently extracted the data using data extraction tables. Any disagreements were resolved by discussion aiming for consensus. Quality assessment
A quality assessment of the included RCTs and controlled clinical studies was performed independently by two reviewers (BB, DTH) according to the Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 (updated March 2011) (Higgins & Green 2011). Three main quality criteria were assessed: allocation concealment, blinding treatment outcomes to outcome examiners and completeness of follow-up. The studies were then rated to have a low risk of bias (all three criteria met) or a high risk of bias (one or more criteria not met). Statistical analysis
Means and standard deviations were calculated for a number of outcome parameters. No meta-analyses could be performed due to heterogeneity in between the studies (different indications, study designs, control groups, observation periods).
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
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Results Study characteristics
The electronic search identified a total of 2396 titles (for details, refer to Fig. 1). From assessing the titles, 2283 were excluded (inter-reader agreement k = 0.98 0.48). The resulting number of abstracts obtained was 113, of which 83 were excluded (inter-reader agreement k = 0.98 0.25). Thirty full-text articles were obtained, seven articles were further excluded after reading the full text. Finally, including studies found through hand searching, nine studies of keratinized tissue and 11 studies of soft tissue volume articles met the inclusion criteria. Exclusion of studies
The reasons for excluding studies (7) after full text was obtained were no reported or insufficient clinical details (n = 3), an insufficient number of patients (n = 1), only hard tissue augmentation (n = 2) and soft tissue augmentation in combination with implant placement and guided bone regeneration (n = 1). Details are provided in Table 1. Included studies
The 20 studies that met the inclusion criteria are presented in Tables 2–5. Tables 2 and 4 represent data for “gain of keratinized tissue” (nine studies) and Tables 3 and 5 refer to clinical studies regarding “soft tissue volume” (11 studies). Increase in width of keratinized mucosa
Patient-based treatment outcomes for the width of keratinized tissue retrieved from nine studies are presented in Tables 2 and 4. Three studies were designed as RCT, two as CCT and the rest of four studies were case series reports. 283 patients and 375 sites were treated for gain of keratinized tissue around the implants. The methods and techniques used for gain of keratinized tissue included no treatment, vestibuloplasty, apically positioned flap/vestibuloplasty (APF/ V) in combination with autogenous tissues FGG, SCTG and APF/V in combination with allogenic grafts (ADMG) or collagen matrices (CM). The mean follow-up period was
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Thoma et al. Basegmez et al. 2012, Lorenzo et al. 2012).
First electronic search: 2396 titles
Treatment outcomes Inter-reader agreement k = 0.98 ± 0.48
Independently selected by 2 reviewers and agreed by both: 113 titles abstracts obtained
Inter-reader agreement k = 0.98 ± 0.25
Independently selected by 2 reviewers and agreed by both: 30 abstracts full text obtained
Excluded: 7
Keratinized tissue: 3
Review: 11
Soft tissue volume: 9
Further handsearching 6 articles on keratinized tissue (references of full text articles)
Further handsearching 2 articles on soft tissue volume (references of full text articles)
Final number of studies included keratinized tissue: 9
Final number of studies included soft tissue volume: 11
Further handsearching 2 articles (references of full text articles)
Final number of reviews included for hand search: 13
Fig. 1. Search strategy.
Table 1. Excluded studies with reason for exclusion Author Alpert (1994) Becker (2001) Bidra & Rungruanganunt (2011) Collins & Nunn (1994) Fagan et al. (2008) Kwakman et al. (1998) Liu & Weisgold (2002)
16.2 months (6–48). The main reason for treating the patients encompassed a lack of or an inadequate with of attached gingival/keratinized tissue. In summary, three studies were eligible for comparison using meta-analyses. The hypothesis of the heterogeneity test could not be rejected (p = 0.43);
Reason for exclusion Only descriptive, no data Hard tissue only Two cases only Hard tissue augmentation only No data, immediate implant placement and soft tissue augmentation at the same time No detailed information about procedures No data, only classifications
therefore, a fixed effects model was chosen. Quality assessment The quality assessment of the included studies revealed a high risk of bias for all included studies except for the three RCTs (Sanz et al. 2009,
Width of keratinized tissue. A total of seven studies (three RCTs, two CCTs, two case series) reported on the width of augmented keratinized tissue. The increase in keratinized tissue ranged between 1.4 and 3.3 mm depending on the technique used. Four studies investigated the efficacy of collagen matrices (Mucograftâ, Geistlich, Wolhusen, Switzerland and Collatapeâ, Zimmer Dental, Carlsbad, CA, USA) (gain between 1.8 and 2.3 mm) or an acellular dermal matrix graft (SureDermTM, Hans Biomed Corp, Seoul, Korea) (gain of 1.4 mm) compared to autogenous grafts (FGG, SCTG) for augmenting the band of keratinized tissue. In two RCTs, the application of a CM (gain of 1.8– 2.3 mm) demonstrated a gain of keratinized tissue as effective and predictable as the gold standard, an autogenous SCTG (gain of 2.3 mm; Sanz et al. 2009, Lorenzo et al. 2012). One study evaluated the changes in width of keratinized tissue following APF/V, APF/V plus CM and APF/V plus FGG. After 3– 4 weeks, the FGG cases showed a greater increase in keratinized tissue (2.5 mm), while the APF/V plus CM (1.8 mm) demonstrated a more physiological and a more favourable morphology than the APF/V only cases (1.6 mm) (Lee et al. 2010). In addition, one study reported on the effects of different time-points for performing FGGs (Stimmelmayr et al. 2011). In this study, no statistical significance (p = 0.562) was found in width of keratinized tissue between FGGs performed at the time of implant placement or at the time of uncovering the implants (Stimmelmayr et al. 2011). The mean gain of keratinized tissue for APF/V plus FGG ranged between 2.2 and 3.3 mm. Percent shrinkage or contraction of keratinized tissue. Two RCTs (Sanz et al. 2009, Basegmez et al. 2012) and one case series (Park 2006) reported post-operative shrinkage or contraction of augmented tissue. All studies found shrinkage of the augmented grafts (SCTG, CM, ADMG, FGG). Only one study reported on
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
NA APF/V in combination with implant placement
NA APF/V plus FGG
2011
2012
2012
Stimmelmayr et al. (2011)
Basegmez et al. (2012)
Bruschi et al. (2012)
Case series
Inadequate width of attached mucosa 3 mm; APF/V2-3 mm; APF/V plus CMminimal; APF/V plus FGG Inadequate width of keratinized mucosa ≤1 mm Inadequate width of keratinized tissue (≤ 3.5 mm) Case series
1991 ten Bruggenkate et al. (1991)
Case series
Inadequate width of keratinized mucosa ≤2 mm on both sides of the implant Inadequate width of attached gingiva Case series
NA APF/V plus CTG APF/V plus CM (Mucograft)
6 APF/V plus FGG APF/V APF/V plus CM (Collatape)
6 APF/V plus SCTG APF/V plus CM (Mucograft)
NA
NA NA
6
NA No treatment
APF/V in combination with implant placement APF/V plus ADMG
18
NA NA APF/V plus FGG
6–32
Control 2 treatment Indication for treatment Study design Year of publication Author
Table 2. Included studies: augmentation of keratinized mucosa
Test treatment
Control 1 treatment
Follow-up period (months)
Soft tissue grafting: a systematic review
S81
% mean graft contraction, revealing more favourable results for the autogenous control group (SCTG; 59.7%) compared to a CM group (67.2%) at 30 days (Sanz et al. 2009). Width of attached mucosa. One RCT study (Basegmez et al. 2012) reported on the efficacy of two techniques (APF/V + FGG or APF/V alone) for increasing the amount of keratinized tissue around the implants. Sixtyfour patients with 64 implants with a minimal keratinized tissue (
